Q31. In a cell, the site of protein synthesis is the
a) Nucleus
b) Ribosome
c) Mitochondrion
d) Golgi apparatus
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Correct Answer: b) Ribosome
Explanation: Ribosomes are the sites of protein synthesis in a cell. They are responsible for translating the genetic code from mRNA into a chain of amino acids, thus constructing proteins.
Q32. What is a primary function of the Golgi apparatus in cellular activities?
a) Energy production
b) Protein synthesis
c) Modifying, sorting, and packaging proteins and lipids
d) DNA replication
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Correct Answer: c) Modifying, sorting, and packaging proteins and lipids
Explanation: The Golgi apparatus plays a crucial role in modifying, sorting, and packaging proteins and lipids that have been synthesized in the endoplasmic reticulum. It prepares these substances for transport to their destination inside or outside the cell.
Q33. Centrioles are cell structures primarily involved in
a) Photosynthesis
b) Cellular respiration
c) Cell division
d) Protein synthesis
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Correct Answer: c) Cell division
Explanation: Centrioles play a key role in cell division in animal cells. They are involved in organizing microtubules that form the spindle fibers during mitosis and meiosis, which are essential for separating chromosomes into daughter cells.
Q34. The semi-permeable nature of the cell membrane allows it to
a) Conduct electrical signals
b) Synthesize proteins
c) Control the movement of substances into and out of the cell
d) Capture light energy
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Correct Answer: c) Control the movement of substances into and out of the cell
Explanation: The cell membrane’s semi-permeable nature allows it to control the movement of substances in and out of the cell. This selective permeability is essential for maintaining the internal environment of the cell.
Q35. The organelle known as the ‘powerhouse of the cell’ due to its role in energy production is the
a) Ribosome
b) Mitochondrion
c) Lysosome
d) Nucleus
Correct Answer: b) Mitochondrion
Explanation: The mitochondrion is known as the ‘powerhouse of the cell’ because it generates most of the cell’s supply of adenosine triphosphate (ATP), used as a source of chemical energy. This energy is crucial for a variety of cellular functions.
Q36. Which type of cell junction forms a barrier to prevent leakage of extracellular fluid across a layer of epithelial cells?
a) Gap junctions
b) Tight junctions
c) Desmosomes
d) Plasmodesmata
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Correct Answer: b) Tight junctions
Explanation: Tight junctions are a type of cell junction that form a barrier to prevent the leakage of extracellular fluid. They are commonly found in epithelial cells and serve to seal adjacent cells together in a tissue.
Q37. Which organelle is responsible for the detoxification of alcohol and other harmful substances?
a) Golgi apparatus
b) Smooth endoplasmic reticulum
c) Lysosome
d) Mitochondria
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Correct Answer: b) Smooth endoplasmic reticulum
Explanation: The smooth endoplasmic reticulum is involved in the detoxification of alcohol and other harmful substances. It plays a significant role in metabolizing and rendering non-toxic various substances that enter the body.
Q38. Microtubules in a cell are primarily made up of
a) Actin
b) Tubulin
c) Keratin
d) Myosin
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Correct Answer: b) Tubulin
Explanation: Microtubules, one of the components of the cell’s cytoskeleton, are primarily made up of tubulin. These tubulin polymers form long, hollow cylinders and are essential for cell shape, division, and intracellular transport.
Q39. What is the role of nucleic acids in cells?
a) Energy storage
b) Providing cell structure
c) Storing and transmitting genetic information
d) Speeding up chemical reactions
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Correct Answer: c) Storing and transmitting genetic information
Explanation: Nucleic acids, such as DNA and RNA, are vital for storing and transmitting genetic information. DNA holds the instructions for building proteins, while RNA transfers this information to the ribosomes for protein synthesis.
Q40. In a cell, vesicles are used for
a) Capturing light energy
b) Transporting materials within the cell
c) Structural support
d) DNA replication
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Correct Answer: b) Transporting materials within the cell
Explanation: Vesicles are small membrane-bound sacs that transport materials within cells. They play important roles in metabolism, transport, buoyancy control, and enzyme storage, among other functions.